The German patent application DE 10 2005 036 410 A1 discloses a method for determining the distribution of the partial pressure of oxygen in at least one portion of a tissue surface. For this purpose a fluorescent dye is applied on the portion of the tissue surface, and is illuminated with excitation light in order to excite fluorescence. During the fluorescence build-up phase at least one first fluorescence image is recorded by means of a camera system, and in the decay phase at least one second fluorescence image is recorded by means of a camera system. Subsequently the fluorescence intensities in the build-up and decay phases are determined from the recorded first and second fluorescence images and the distribution of the oxygen partial pressure in the at least one portion of the tissue surface is found by forming the ratio of the determined fluorescence intensities.
The article “Functional and structural imaging of phototrophic microbial communities and symbioses” by Michael Kühl and Lubos Polerecky, Aquat Microb Ecol 53 (2008), 99, doi 10.3354/ame01224, describes the imaging of a cell community with simultaneous representation of the oxygen distribution by a transparent sensor. The transparent sensor therein is applied as a homogeneous layer on a carrier.
In examining objects like tissue samples with respect to the distribution of a substance contained therein it is advantageous to show the tissue sample and the distribution of the substance in a single image. If suitable transparent sensors are available for the substance in question, like in the case of oxygen mentioned above, an image can be captured through the sensor. Such transparent sensors, however, are not available for all interesting substances.
The international patent application WO 2002/056023 A1 discloses an optical sensor for determining at least one parameter in a sample. The sensor contains an indicator material sensitive to the parameter with a short decay time, and a reference material not sensitive to the parameter with a long decay time, and serves for capturing a measurement signal indicating the parameter to be determined. The measurement is based on luminescence responses of both the indicator and the reference material captured together. The indicator and the reference material are immobilised on a common carrier.
The international patent application WO 2002/103334 A1 relates to a sensor type in which microtitre plates or carriers with recesses for holding samples, are used to measure oxygen. Luminescent or fluorescent dyes (for example platinum, palladium, or ruthenium complexes with phenanthroline, porphyrine, or pyridine ligands) are contained in the wells of the microtitre plates, wherein the dyes are embedded in particles of a matrix permeable for gas but impermeable for water. The matrix is a derivative of polystyrene or a polystyrene copolymer. The particles in turn are dispersed in a second matrix permeable for water, which comprises a hydrophilic polymer, like for example polyhydroxymethacrylate, polyvinyl alcohol, or polyvinylpyrrolidone.
The European patent EP 1 414 336 B1 serves for the visualisation of fluorescent dyes for fluorescence diagnostics of, for example, tumours in humans, and is also particularly suited for a highly sensitive, quantitative early detection of a plurality of precancerous/dysplastic mutations. A digital camera system with a 3-CCD-chip (also RGB chip) is provided as optoelectric image converter. A control electronics is provided for a pulsed light source, generating the excitation light.
The European patent EP 1 130 382 B1 discloses an apparatus for analysing multiple parameters in a liquid simultaneously. The apparatus comprises a plurality of sensors, a light source for providing the light, in order to excite the sensors. Each sensor of each group has a different chemical, interacting specifically with the parameter. The differences with respect to the sensors lead to differences with respect to the light-interaction.